What is a Gasket?
According to Wikipedia, “A gasket is a mechanical seal which fills the space between two or more mating surfaces, generally to prevent leakage from or into the joined objects while under compression.”
Gaskets allow “less-than-perfect” mating surfaces on machine parts where they can fill irregularities. Gaskets are commonly produced by cutting from sheet materials. They allow for specific applications, such as high pressure steam systems, may contain asbestos. However, due to health hazards associated with asbestos exposure, non-asbestos gasket materials are used when practical. Gaskets can be cut from a drawing or from a sample of the gasket required. Simple shapes can be cut by hand and for more complicated shapes a die maybe required.
Materials
There are two types of gaskets: Metal Gaskets and Elastomers
Metal
Flat Solid: Cut from sheet metal, these gaskets can be of unlimited size and shape. Mating surfaces need to be perfectly aligned and flat for metal gaskets to provide good seals.
Profiled and Serrated: A solid gasket with surface grooves facilitating a good seal with lower seating stresses. These styles can be jacketed to protect the flange surfaces.
Corrugated: Made from thin metal, these gaskets provide a seal at low seating stress. They may be surface-treated with ceramic, non-asbestos or flexible graphite.
Elastomers
Elastomeric Gaskets are made of one type of solid rubber which is either cut from a sheet/roll or moulded/extruded to a specification. These gaskets are suited for low pressure, low heat environments and will create a seal with a low bolt load. This is ideal for flanges that use low grade low quality bolts and/or non-asme flanges and joints. O-rings fall into this class of gasket and are particularly suited to tongue and groove applications.
- Natural Rubber – Excellent physical properties including abrasion and low temperature resistance. Poor resistance to petroleum-based fluids.
- Urethane – Good aging and excellent abrasion, tear, and solvent resistance. Poor high temperature properties.
- Neoprene – Good weathering resistance. Flame retarding. Moderate resistance to petroleum-based fluids. Good physical properties.
- Nitrile – Excellent resistance to petroleum-based fluids. Good physical properties.
- Butyl – Very good weathering resistance. Excellent dielectric properties. Low permeability to air. Good physical properties. Poor resistance to petroleum-based fluids.
- EPDM – Excellent ozone, chemical, and aging resistance. Poor resistance to petroleum-based fluids.
- Styrene Butadiene (Buna-S, SBR) – Excellent abrasion resistance and low temperature properties. High resilience.
- Silicone – Excellent high and low temperature properties. Fair physical properties.
- Hypalon – Excellent ozone, weathering, and acid resistance. Good abrasion and heat resistance. Fair resistance to petroleum-based fluids.
- Viton – Excellent oil and air resistance both low and high temperatures. Very good chemical resistance.1 “Sheet Rubber Handbook – Gasket and Packing Materials”, Rubber Manufacturers Association (RMA) & The Rubber Association of Canada
Bryan Hose & Gasket prides themselves in using non-asbestos products! We provide a large inventory of general purpose as well as specialized non-asbestos sheet and can cut your gaskets to your specifications. Our gasket materials are used through out the world. These materials are engineered to exact specifications.